How quickly do domestic rats grow? - briefly
Domestic rats attain sexual maturity around 5–6 weeks and reach full adult size (≈250–300 g) by 3–4 months. Initial growth is rapid, averaging about 30 g per week, then decelerates after the first month.
How quickly do domestic rats grow? - in detail
Domestic rats reach full size within a short span of time. After a gestation period of approximately 21–23 days, neonates weigh between 5 and 7 g. Their early growth follows a predictable pattern:
- First week: Weight increases to about 15–20 g; eyes open and fur appears.
- Second week: Weight reaches 30–35 g; teeth erupt, and the pups begin to explore the cage.
- Third week: Weight approaches 45–50 g; solid food intake becomes dominant, and weaning is complete around day 21.
- Fourth week: Weight climbs to 60–70 g; locomotor skills are fully developed.
- Fifth to sixth week: Weight stabilizes near 120–150 g, the typical adult mass for most laboratory strains.
Sexual maturity occurs between 5 and 8 weeks, varying with strain, sex, and nutrition. Males may become fertile as early as 6 weeks, while females often require 8 weeks. Growth rate slows after the fifth week, with most skeletal growth completed by 10 weeks.
Key factors influencing the speed of development include:
- Genetics: Certain strains (e.g., Sprague‑Dawley) exhibit faster growth than others (e.g., Long‑Evans).
- Diet: High‑protein, balanced diets accelerate weight gain; caloric restriction delays maturation.
- Environment: Ambient temperature, cage density, and stress levels can modify growth curves.
Monitoring weight weekly provides a reliable indicator of health and development. Sudden deviations from the expected trajectory may signal illness, inadequate nutrition, or environmental stress.